Impact of environmental pollution on acne: a systematic review

In an increasingly urbanized world, environmental pollution is recognized for its adverse effects on both systemic and skin health. While its role in conditions such as atopic dermatitis and psoriasis is well documented, its impact on acne vulgaris remains less clear. This review aims to evaluate existing literature examining the association between environmental pollutants - such as particulate matter (PM_2.5, PM₁₀), nitrogen oxides (NO₂, NO_x) and traffic-related emissions - and the development, severity or exacerbation of acne. A systematic search of peer-reviewed English-language studies published between 2010 and 2025 was conducted using PubMed. Search terms included 'air pollution', 'particulate matter', 'PM_2.5', 'PM₁₀', 'NO₂', 'NO_x', 'environmental pollution', 'traffic pollution', 'acne' and 'acne vulgaris'. Studies were included if they investigated the relationship between environmental pollutants and acne in human populations. Of the 27 studies identified, 17 met inclusion criteria. Systematic reviews were also incorporated to provide broader context. Several studies demonstrated significant associations between pollutant exposure and acne exacerbation. A time-series study in China involving 71 625 outpatient visits found that each 10 μg m^-3 increase in SO₂ and NO₂ correlated with 1.02% and 2.13% increases in acne-related visits, respectively. Other studies appear to show pollutants being associated with increased sebum production and reduction of antioxidants. Proposed mechanisms include oxidative stress, microbiome disruption and follicular hyperkeratinization. However, study heterogeneity, lack of diversity and limited control for confounders limit generalizability. Longitudinal research is needed to clarify pollution's role in acne and inform targeted prevention strategies.